Motorcycle engines tend to heat up while in use, and typically rely at least in part on a flow of air over the engine and/or radiator to cool the engine. In one particular type of engine, the two-cylinder V-twin engine, the cylinders are commonly provided with fins to provide a large surface area for heat transfer from the engine to the air flowing over the engine. During such heat transfer, the air flowing over the engine is heated, which may cause discomfort to a motorcycle rider due to the proximity of the rider's legs to the engine.
Additionally, some motorcycle engines have one cylinder disposed behind another cylinder with respect to the direction of travel of the motorcycle. This is true of many V-twin motorcycle engines, as well as other multi-cylinder motorcycle engines. In such cases where one cylinder is disposed in front of another cylinder, the front cylinder may block the flow of air to the rear cylinder, causing the rear cylinder to become hotter than the front cylinder. Such uneven heating of the cylinders may result in one cylinder performing differently than the other cylinder, which may lead to inefficiencies in engine operation.